Friend brought this to me saying it was the classis "Tubes Light - No Sound" He was sort of right?! Once you turn the volume up to half or more you get an awful distortion crackly sound.... if you hit the strings lightly, you get mostly nothing. SO far I just checked the board for obvious issues and while running a limiter I checked to see if I could catch any DC passing the board caps.... didn't disconnect any. Anyone seen this problem?? Thoughts?